Applied Research Of The Digital Up And Down Converter Technology And Its Implementation Of FPGA In GSM System

The GSM system has gained great success as the world’s first digital cellularcommunication standard. With the continuous development of mobile communication,new technologies will inevitably introduce into next generation base station. Thesoftware radio technology is one of them. These advanced technologies are introducedinto the GSM system, can achieve the integration of GSM network with nextgeneration networks, and further enhance the carrying capacity of GSM, and morepaved the way for future development.The core of the software radio is loaded with different communication softwaremodules in a common, open, standardization and modular communication hardwareplatforms, and achieve the conversion of different modes of communication on thecommon hardware platform. Its conception is to make wideband A/D and D/Aconverter as close as possible to the antenna, and as much as possible to complete avariety of processing in the digital domain. But by the limitations of the currentdevices on the signal processing rate, at this stage could not be directly processed onthe RF, so using the IF scheme, achieving the rate conversion of the signal by digitalup/down converter system, to establish a bridge between the A/D/A converter withthe digital signal processing unit, which will help the system front-end signalprocessing.Field programmable gate array (FPGA) is programmable device which based onlook-up table, it has a significant parallel processing capability and real-timeprocessing capability, and integrates a large number of digital signal processing IP core, and thus become a good choice with real-time processing.This paper has designed multi-channel software radio digital up/down convertersystem which is based on the GSM system, and be realized by the FPGA.In this paper, studied the basic theory of software radio in-depth: includingNaquist low-pass and band-pass sampling theorem; also researched the basic theory ofsignal processing of the software radio: including of multi-rate signal processingtheory and digital signal orthogonal transform theory; with a brief introduction toGSM system and the technical principles of multi-carrier; mathematical modelingmulti-channel software radio receivers and transmitters in GSM system with Matlab,and then established the architecture by demonstrating of digital up/down converterin GSM system.After established the digital up/down converter overall design scheme in GSMsystem, modeling integrator comb CIC decimation/interpolation filter module,half-band decimation/interpolation filter module and FIR compensation filter modulewith the Matlab, achieving optimized design on the basis of traditional realized,including Hogenauer decimation/interpolation filter, Semi-parallel architecturehalf-band filter and the DA algorithm FIR compensation filter.Finally, used of Verilog HDL language and IP core, and through Modelsimsimulation, to achieve the optimum design of various module of digital up/downconverter in GSM system, given out the RTL level chart and external interface ofeach module; then use the top-level file calls the design of each module, at last, thesystem was integrated and verified. At the same time gives the results of the analysisof digital up/down converter in GSM system.